In conditions such that primary fragments from photolysis of nitrite (fragments include NO) are prevented from efficient back reaction, secondary reactions are known to yield a wide range of products and the proposed research project would investigate whether nitros amines or other carcinogenic nitrogen-containing species are among the photolysis products in nitrite or nitrite-treated foods. Appropriate samples would be exposed to near uv-illumination similar to that encountered in food handling, storage and display, and then monitored for nitrogen containing carcinogens, utilizing a range of techniques. Specific chemical analysis for nitros amines by established procedures would be supplemented by electron spin resonance studies, since the sensitivity of this technique for free-radical intermediates, such as nitroxides, greatly exceeds that of other techniques. Furthermore, nitros amines may act as highly efficient radical "traps" converting other radicals to nitroxides thereby revealing their own presence via a steady state concentration of nitroxide radicals in the illuminated system. Facilities and techniques for in-situ exposure of suspensions to near uv-illumination have already been developed and the feasibility of detecting nitros amines through spin trapping would be explored. Treatment with nitrogen-15 labelled nitrite or nitrate would be utilized, where appropriate, in testing if intermediates originated from such treatment.